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(#) Incorrect constant

!!! ERROR: Incorrect constant
   This is an error.

Id
:   `WrongConstant`
Summary
:   Incorrect constant
Severity
:   Error
Category
:   Correctness
Platform
:   Android
Vendor
:   Android Open Source Project
Feedback
:   https://issuetracker.google.com/issues/new?component=192708
Since
:   3.1.0 (March 2018)
Affects
:   Kotlin and Java files
Editing
:   This check runs on the fly in the IDE editor
Implementation
:   [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/TypedefDetector.kt)
Tests
:   [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/TypedefDetectorTest.kt)

Ensures that when parameter in a method only allows a specific set of
constants, calls obey those rules.

!!! Tip
   This lint check has an associated quickfix available in the IDE.

(##) Example

Here is an example of lint warnings produced by this check:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text
src/DetailInfoTab.kt:9:Error: Must be one of: View.LAYOUT_DIRECTION_LTR,
View.LAYOUT_DIRECTION_RTL, View.LAYOUT_DIRECTION_INHERIT,
View.LAYOUT_DIRECTION_LOCALE [WrongConstant]
    view.layoutDirection = View.TEXT_ALIGNMENT_TEXT_START // ERROR - not one of the allowed values
                           ------------------------------
src/DetailInfoTab.kt:28:Error: Must be one of: DetailInfoTabKt.CONST_1,
DetailInfoTabKt.CONST_2, DetailInfoTabKt.CONST_3 [WrongConstant]
    test(UNRELATED) // ERROR - not part of the @DetailsInfoTab list
         ---------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here is the source file referenced above:

`src/DetailInfoTab.kt`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~kotlin linenumbers
import android.view.View
import androidx.annotation.IntDef

// Example of using Android API already annotated with @IntDef:

fun setAlignment(view: View) {
    view.layoutDirection = View.LAYOUT_DIRECTION_RTL // OK
    view.layoutDirection = View.TEXT_ALIGNMENT_TEXT_START // ERROR - not one of the allowed values
}

// Custom example creating your own typedef:

const val CONST_1 = -1
const val CONST_2 = 2
const val CONST_3 = 0
const val UNRELATED = 1

@IntDef(CONST_1, CONST_2, CONST_3)
@Retention(AnnotationRetention.SOURCE)
annotation class DetailInfoTab

fun test(@DetailInfoTab tab: Int) {
}

fun test() {
    test(CONST_1) // OK
    test(UNRELATED) // ERROR - not part of the @DetailsInfoTab list
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can also visit the
[source code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/TypedefDetectorTest.kt)
for the unit tests for this check to see additional scenarios.

(##) Suppressing

You can suppress false positives using one of the following mechanisms:

* Using a suppression annotation like this on the enclosing
  element:

  ```kt
  // Kotlin
  @Suppress("WrongConstant")
  fun method() {
     problematicStatement()
  }
  ```

  or

  ```java
  // Java
  @SuppressWarnings("WrongConstant")
  void method() {
     problematicStatement();
  }
  ```

* Using a suppression comment like this on the line above:

  ```kt
  //noinspection WrongConstant
  problematicStatement()
  ```

* Using a special `lint.xml` file in the source tree which turns off
  the check in that folder and any sub folder. A simple file might look
  like this:
  ```xml
  &lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;lint&gt;
      &lt;issue id="WrongConstant" severity="ignore" /&gt;
  &lt;/lint&gt;
  ```
  Instead of `ignore` you can also change the severity here, for
  example from `error` to `warning`. You can find additional
  documentation on how to filter issues by path, regular expression and
  so on
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html).

* In Gradle projects, using the DSL syntax to configure lint. For
  example, you can use something like
  ```gradle
  lintOptions {
      disable 'WrongConstant'
  }
  ```
  In Android projects this should be nested inside an `android { }`
  block.

* For manual invocations of `lint`, using the `--ignore` flag:
  ```
  $ lint --ignore WrongConstant ...`
  ```

* Last, but not least, using baselines, as discussed
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).

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